The experiments to be conducted include studies of: 1. The mode of action of caltrin by comparing its effects on Ca transport by bovine epididymal spermatozoa provided with a variety of energy sources. The effect of caltrin on liver and heart mitochondrial Ca transport will also be investigated. 2. The presence of proteins with structures and functions similar to those of caltrin will be studied in guinea pigs, dogs, rabbits and rams. 3. The cause of enzyme "down regulation" during vigorous exercise will be sought. 4. The role of sn-glycerol-3-phosphate dehydrogenase in thermogenesis and metabolic regulation will be continued using a number of new drugs that cause weight loss in obese animals and improve glucose utilization in diabetic animals. 5. The mechanism by which gluconeogenic hormones increase liver malate concentration, and therefore increased substrate utilization will be investigated.